The subject matter described herein relates generally to methods and systems for wind turbines, and more particularly, to methods and systems concerning a shadow flicker protection system of a wind turbine.
Wind energy harvested, for example, through the use of large scale wind turbines has experienced rapid growth in recent years. Sources of this growth may be the numerous environmental, technical and economic benefits related to wind generated energy production. Wind energy is widely available, renewable and reduces the production of greenhouse gases by diminishing the need of fossil fuels as energy source. Furthermore, technical developments have improved design, manufacturing technologies, materials and power electronic devices of wind turbines and will in the future continue to decrease production costs of wind turbines while increasing their energy production capabilities and efficiencies.
At least some known wind turbines include a tower and a nacelle mounted on the tower. A rotor is rotatably mounted to the nacelle and is coupled to a generator by a shaft. A plurality of blades extend from the rotor. The blades are oriented such that wind passing over the blades turns the rotor and rotates the shaft, thereby driving the generator to generate electricity.
Wind turbines may be placed individually or in groups, also known as wind farms, in on- or off-shore environments. When the wind turbine is placed in the proximity of a residential area, it is possible when the sun is unfavorable positions, that the wind turbine or rotor thereof is between the sun and a residence of the residential area. If the sunshine is not affected by dark clouds, the rotating rotor constantly throws a shadow on to the residence or property thereof. The shadow casting, also known as shadow flicker, caused by a wind turbine on the adjoining properties is often perceived by the residents as being very troublesome and may spook animals, such as animals grazing in the proximity of a wind turbine.
A number of factors such as the position and point of the sun and cloudiness may influence the shadow flicker behavior of wind turbines. In the northern hemisphere, the risk for shadow flickering is largest in spring, autumn and winter as well as sunrise and sunset. Therefore, even if the wind turbine satisfies the legal approval requirements, there is however not always any guarantee that the undesired shadow casting effect is prevented.
The effect of shadow flicker may be resolved by the use of wind turbine shut-down systems that use a plurality of expensive light sensitive sensors typically positioned in different locations to determine the shadow casting behavior of a wind turbine. In particular, the multiple light sensors are used to determine light intensity at different regions, i.e., in a shadowed region and in a light region with direct light incidence (direct sun irradiation). Such shut-down systems often have a complex set-up and wiring. Each light sensitive sensor is prone to failure. If one of the light sensors fails, the shut-down system fails. This causes such shut-down systems to be unnecessarily un-reliable, expensive and to have a high cost of ownership.
Hence, it will be appreciated that a more cost efficient, reliable and simpler shut-down system is desired. The subject matter described herein pertains to such a system and method of use thereof, amongst other things, by improving the reliability of such shut-down systems.